Transmission bandwidth demands in telecommunication networks (e.g., the Internet) appear to be ever increasing and solutions are being sought to support this bandwidth demand. One solution to problem is to use optical networks, where wavelength-division-multiplexing (WDM) technology is used to support the ever-growing demand for higher data rates. Commonly used optical components include Bragg gratings.
Bragg gratings can be implemented in optical fibers (i.e., also known as fiber Bragg gratings or FBGs) or in integrated circuits (i.e., also known as waveguide Bragg gratings or WBGs). WBGs are considered to be one of the key components for future WDM systems and networks.
WBGs are typically realized as surface corrugated grating structures. Typical surface corrugated WBGs have relatively large spectral sidelobes. Conventional solutions to reduce spectral sidelobes in surface corrugated WBGs include using e-beam lithography to form cascaded uniform gratings, each uniform grating having a different fixed duty-cycle. However, e-beam lithography is relatively costly and complex.